This invention relates to a system for jointing panels, and in particular for jointing metal panels to form a sheet for the roofing or cladding of buildings.
Sheet coverings are in widespread use on buildings, particularly for roofing. Narrow panels are laid parallel to the slope of a roof on top of a timber deck which provides support. These panels are then joined to form a sheet. It is necessary to ventilate the roof space and the underside of the covering to the atmosphere to avoid condensation.
However since this form of roofing was introduced, the need to conserve energy has been recognised. To this end roof structures are now provided with insulation, and gratuitous air movements eliminated from roof spaces. This reduction of the natural ventilation of buildings has the concomitant effect of increasing condensation therein, the evaporation of which is precluded by the necessary imperviousness to vapour of the materials of which the sheet coverings are formed.
In addition, although sheet coverings are adequate in most weather conditions, their performance in severe storms is unpredictable. For example, when subjected to negative wind loads, pressure differences across a sheet roof covering will cause it to deflect upwards.
Thus two serious problems with sheet roofing, limiting both performance and lifespan, are condensation and wind damage by suction. The present invention addresses both problems by providing means simultaneously to ventilate the underside of roofs and prevent the upward deflection of roofing panels.
U.S. Pat. No. 2,635,332 describes a system for jointing a first panel and a second panel overlying a support structure comprising a retaining member fixable to the support structure and having a first portion adapted to retain a side of said first panel and a second portion adapted to retain a side of said second panel; and a cap having a cross-section of generally inverted U-shape and configured substantially to enclose said retaining member, wherein said cap has inwardly directed projections from the sides of the cap forming the vertical legs of the U-shape.
DE-A-3 741 379 and FR-A-1 112 077 also show similar systems for jointing a first panel and a second panel overlying a support structure.
According to a first aspect of the present invention there is provided a system for jointing a first panel and a second panel overlying a support structure comprising a retaining member fixable to the support structure and having a first portion adapted to retain a side of said first panel and a second portion adapted to retain a side of said second panel; and a cap having a cross-section of generally inverted U-shape and configured substantially to enclose said retaining member; characterised in that said cap is configured to permit the circulation of air and preclude the entry of water or the like, from above the system.
Preferably said cap has projections from the sides of the cap forming the vertical legs of the U-shape, said projections being perforated.
Preferably said system is for jointing a first metal panel and a second metal panel.
Preferably the cap is held in place by cooperation with at least one retaining member.
Preferably the cap is configured to `click-fit` said at least one retaining member.
Preferably said projections are deformable to engage a retaining member to achieve said `click-fit`.
Preferably said retaining member is in the form of a generally M-shaped clip. Said clip may be made from stainless steel. More preferably said clip is made from 3 mm stainless steel.
Preferably the legs of said clip are shorter than the sides of said panels which they retain, in order that there is a gap between the termination of a leg and the face of a panel.
Further according to the present invention there is provided a roofing system comprising:
metal panels with upturned sides running substantially parallel; PA1 a support structure; PA1 a retaining member fixable to the support structure and adapted to contain the sides of adjacent panels; and PA1 a cap having a cross-section of generally inverted U-shape and configured substantially to enclose said retaining member; PA1 characterised in that said cap has projections from the sides of the cap forming the vertical legs of the U-shape, said projections being perforated.
Preferably said metal panels lie orthogonal to the support structure thereby defining a cross grid.
Further according to the present invention there is provided a cap for use in the system of claim 1 characterised in that said cap is of cross-section of generally inverted U-shape and has projections from the sides of the cap forming the vertical legs of the U-shape, said projections being perforated.